Csp3/Csp2-H functionalized oxidative [3+2+1] cyclization for Synthesis of Pyrido[2,3-d]pyrimidines

A variety of Pyrido[2,3-d]pyrimidines derivatives have been synthesized via Csp3/Csp2-H functionalization of readily available methyl arenes, 6-amino uracil, and malononitrile using K2S2O8 under metal-free and environmentally benign conditions. By using methyl arenes as the C4 source of the Pyrido[2,3-d]pyrimidines skeleton, this synthetic strategy provides a series of Pyrido[2,3-d]pyrimidines via an oxidative [3+2+1] cyclization process.